Concurrent Programming Model and Best Practices in Java Class Libraries in Java Class Library)
Concurrent programming model and best practice in the Java class library
In Java programming, it is very important to use the concurrent programming model when a large number of concurrent tasks need to be processed.Java provides many types of libraries and tools for implementing concurrent programming, and also provides some best practices to ensure the correctness and efficiency of concurrent operations.This article will introduce the Concurrent programming model and some best practices in the Java class library, and explain it through the Java code example.
1. Parallel programming model
1. Thread: Java provides a Thread class to express the complicated thread.You can create a thread by inheriting the Thread class or implementing the Runnable interface, and to start the execution of the thread through the Start () method.
Example code:
class MyThread extends Thread {
public void run() {
// The execution logic of the thread
}
}
public class Main {
public static void main(String[] args) {
Thread thread = new MyThread();
thread.start();
}
}
2. Thread Pool: When facing a large number of concurrent tasks, creating and destroyed threads will bring a certain amount of expenses.In order to avoid frequent creation and destruction of threads, the thread pool can be used to manage the life cycle of the thread.Java provides the Executor framework to achieve the function of the thread pool.
Example code:
ExecutorService executor = Executors.newFixedThreadPool(5);
for (int i = 0; i < 10; i++) {
Runnable worker = new MyRunnable();
executor.execute(worker);
}
executor.shutdown();
3. Synchronization: In a multi -threaded environment, when multiple threads access shared resources at the same time, it may cause data inconsistency or errors.To avoid this, the synchronization mechanism can be used to ensure the access order and consistency of shared resources.
Example code:
class Counter {
private int count;
public synchronized void increment() {
count++;
}
public synchronized int getCount() {
return count;
}
}
2. Best practice
1. Concurrent Collection: Java class library provides a series of concurrent sets, such as ConcurrenThashMap, CopyonWriteArrayList, etc.These classes can securely share data between multiple threads and provide some efficient concurrent operation methods.
Example code:
ConcurrentMap<String, Integer> map = new ConcurrentHashMap<>();
map.put("key", 1);
int value = map.get("key");
2. Avoid the use of Mutable State: Sharing status refers to variable data shared between multiple threads.In concurrent programming, sharing status is one of the main sources of thread security issues.In order to avoid thread security issues, try to avoid the use of sharing status or use thread security to access the shared state.
Example code:
// Unsafe sharing status
class Counter {
private int count;
public void increment() {
count++;
}
public int getCount() {
return count;
}
}
// Safe sharing status
class Counter {
private AtomicInteger count = new AtomicInteger();
public void increment() {
count.incrementAndGet();
}
public int getCount() {
return count.get();
}
}
3. Use the lock to protect the critical section: in a multi -threaded environment, when multiple threads access the critical area at the same time, it may lead to data incompetence.In order to ensure the execution order and security of the critical area, the lock can be used for synchronous operations.
Example code:
class Counter {
private int count;
private Lock lock = new ReentrantLock();
public void increment() {
lock.lock();
try {
count++;
} finally {
lock.unlock();
}
}
public int getCount() {
lock.lock();
try {
return count;
} finally {
lock.unlock();
}
}
}
Summarize:
This article introduces the Concurrent programming model and some best practices in the Java class library.By using thread, thread pool, synchronization mechanism, etc., highly efficient and secure concurrency procedures can be written.At the same time, the use of concurrent sets and avoiding the use of sharing status and locks to protect the critical area is also the key to improving the performance and correctness of concurrent program.I hope this article will provide some help and guidance in your Java concurrent programming.
